Vaso-occlusive coil with conical end

ABSTRACT

This is an implantable vaso-occlusive coil which is implanted using minimally invasive surgical techniques. It is a complex, helically wound coil made up of a primary helically wound coil which is then wound into a specific secondary shape. The secondary shape is itself a series of helical turns. At least a portion of the turns in the secondary shape form a cylindrical region and adjacent that region on at least one end is a conical region which tapers from a diameter approximating that of the central cylindrical region to a smaller diameter. The device is desirably self-forming upon exit from the distal end of a delivery catheter. Also, the conical tipped vaso-occlusive device may also utilize thrombus-enhancing filamentary material.

FIELD OF THE INVENTION

This invention is an implantable vaso-occlusive coil which is implantedusing minimally invasive surgical techniques. It is a complex, helicallywound coil made up of a primary helically wound coil which is then woundinto a specific secondary shape. The secondary shape is itself a seriesof helical turns. At least a portion of the turns in the secondary shapeform a cylindrical region and adjacent that region on at least one endis a conical region which tapers from a diameter approximating that ofthe central cylindrical region to a smaller diameter. The device isdesirably self-forming upon exit from the distal end of a deliverycatheter. Also, the conical tipped vaso-occlusive device may alsoutilize thrombus-enhancing filamentary material.

BACKGROUND OF THE INVENTION

Vaso-occlusive devices are surgical implements or implants that areplaced within some opening in the human body. Typically the opening iseither within the vasculature or some other region which is to beoccluded. Such other sites include fallopian tubes and bile ducts. Theyare delivered typically via a catheter. It is intended that the deviceseither block the flow of blood through a vessel making up that portionof the vasculature via the formation of an embolus. An embolus may alsobe formed within an aneurysm stemming from a normal vessel by use ofthis invention.

One such widely used device is the helically wound vaso-occlusive coil.Many such coils are dimensioned to engage the walls of the vessels orother sites they are intended to occlude. Other significantly less stiffhelically wound devices have also been described in the literature.

A patent describing an early vaso-occlusive device which patent,parenthetically, also provides an excellent background to thevaso-occlusive technology at that time is Ritchart et al. (U.S. Pat. No.4,994,069). Ritchart et al. describes a vaso-occlusive coil that assumesa linear helical configuration when stretched and a folded, convolutedconfiguration when released from the catheter. The stretched conditionis used in placing the coil at the desired site via passage through thecatheter. The coil assumes a relaxed configuration--which is bettersuited to occlude the vessel--once the device is released from thecatheter. Ritchart et al describes a variety of secondary shapesincluding "flower" shapes and double vortices.

The use of vaso-occlusive coils having attached fibrous elements in avariety of secondary shapes is shown in Chee et al. (U.S. Pat. No.5,304,194). Chee et al. describes a helically wound device having asecondary shape in which the fibrous elements extend in a sinusoidalfashion down the length of the coil. These coils, as with the Ritchartet al. coils, are produced in such a way that they will pass through thelumen of a catheter in a generally straight configuration and, whenreleased from the catheter, form a relaxed or secondary shape in thelumen or cavity chosen within the human body. The fibrous elements shownin Chee et al. enhance the ability of the coil to fill space within thevasculature and to facilitate formation of an embolus and subsequentallied tissue.

There are a variety of ways of placing shaped and linear coils into thehuman vasculature. In addition to those patents which are believed todescribe only the physical pushing of a coil out into the vasculature,(e.g., Ritchart et al.), there are a number of other ways to release acoil at a specifically chosen time and site. For instance, U.S. Pat.Nos. 5,354,295 and its parent U.S. Pat. No. 5,122,136, both to Guglielmiet al. describe a device which is electrolytically detachable from itspusher wire.

A variety of mechanically detachable devices is also known. Forinstance, U.S. Pat. No. 5,234,437, to Sepetka, shows a coil which ishelically unwound from a pusher having an interlocking surface. U.S.Pat. No. 5,250,071, to Palermo, shows an embolic coil assembly usinginterlocking clasps mounted both on the pusher and on the embolic coil.U.S. Pat. No. 5,261,916, to Engelson, shows a detachablepusher-vaso-occlusive coil assembly having an interlock ball andkeyway-type coupling. U.S. Pat. No. 5,304,195, to Twyford et al., showsa pusher-vaso-occlusive coil assembly having an affixed, proximallyextending wire carrying a ball on its proximal end and a pusher having asimilar end. The two ends are interlocked and disengage when the coil isejected from the distal end of the catheter. U.S. Pat. No. 5,312,415, toPalermo, shows a multiple coil device in which the coils are placed on asingle pusher in the form of a guidewire which has a section capable ofinterconnecting with the interior of the helically wound coil. U.S. Pat.No. 5,350,397, to Palermo et al., shows a pusher having a throat at itsdistal end and a pusher through its axis. The pusher sheath will holdonto the end of an embolic coil and the embolic coil will then bereleased upon pushing of the axially placed pusher wire against theproximal portion of the vaso-occlusive coil.

Vaso-occlusive coils having little or no inherent secondary shape havealso been described. For instance, in U.S. patent application Ser. No.07/978,320, filed on Nov. 18, 1992, entitled "Ultrasoft Embolism CoilsWith Fluid-Like Properties" by Berenstein et al. is coil having littleor no shape after introduction into the vascular space.

A variety of other patent applications assigned to Target Therapeutics,Inc., of Fremont, Calif. describe coils or other related vaso-occlusivedevices having specific shapes. Of particular interest is U.S. designpatent application Ser. No. 29/037,001 filed Mar. 31, 1995 for spiralvaso-occlusive coils by Mariant et al.

None of these previously-described devices or self-forming helicallywound coils which self-form into secondary structures having opposingconical end separated by a generally cylindrical portion between thoseopposing ends.

SUMMARY OF THE INVENTION

This invention is a vaso-occlusive device comprising a helically woundcoil which is formed by winding a wire into a first helix or form; thefirst helix is then itself wound into a secondary form. The secondaryform is one which, once ejected from a delivery catheter, forms a shapehaving conical section at each opposing end, which conical end diameterdecreases to the furthermost points of the device. It generally forms a"submarine" type shape. Desirably, the vaso-occlusive device is of asize and shape suitable for fitting within a vascular cavity (e.g., ananeurysm, perhaps, a fistula). Stiffness of various parts of the coilmay be tailored or selected to enhance the ability of the device for itsspecific applications. Fibrous materials may be woven into the member ortied or wrapped onto it.

The device may be made in a variety of ways. Typically, the member ishelically wound in a generally linear fashion to form a first or primarywinding. After completion of that step, the primary winding is thenwound around an appropriately shaped winding fixture or form and theso-wound assembly is heat treated to help it retain its shape afterremoval from the winding fixture. Auxiliary fibrous materials are thenadded by weaving, tying, or other suitable permanent attachment methods.

The device is used simply by temporarily straightening device andintroducing it into a suitable catheter, the catheter already havingbeen situated so that its distal opening is within the mouth of thevascular cavity or opening to be filled. The device is then pushedthrough the catheter and, upon its ejection from the distal end of thecatheter into the vascular cavity, assumes its relaxed shape.

The device is typically used in human vasculature to form emboli but maybe used in any site in the human body or occlusion such as one producedby the inventive device is desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a variation of the inventive vaso-occlusivedevice having but a single cone-shaped end and a cylindrical centersection.

FIG. 2 shows a side view of another variation of the inventive devicehaving conical portions at each end.

FIG. 3 shows another variation of the inventive device in which theangles of the two conical ends of the device are substantiallydifferent.

FIG. 4 shows a cross section of the FIG. 3 device showing the interiorof fiber placement.

FIG. 5 is a close-up partial side view of a primary coil useful in thisinvention showing tufted fibers.

FIG. 6 shows an electrolytically erodible joint useful in deploying thisinventive vaso-occlusive device.

FIG. 7 is a partial cross section side view of a mechanically detachablejoint suitable for use with this invention.

DESCRIPTION OF THE INVENTION

This invention is a vaso-occlusive device comprising one or morevaso-occlusive helical coils which are formed by winding a wire into afirst helix; the first helix is then wound into a secondary form. Thesecondary form may be held or restrained within a tubular body such as acatheter or introducer into a shape which approximates the shape of theinterior of that tubular body. The secondary form is one which, whenejected or pushed from the delivery catheter has a plurality of turns atleast one substantially conical portion adjacent to a centralcylindrical portion having a diameter approximating the larger end ofthe conical end. Preferably the device has opposing conical endsseparated by a cylindrical coil section.

FIG. 1 shows the most basic variation of (100) of the basic inventivedevice. In particular, vaso-occlusive device (100), has a generallycylindrical section (102) also known as the mid-section (102) made up ofa number of turns (103) helically wound of a primary coil which in turnwas helically wound from a wire. The end section (104) has a large endwhich continues on from the primary winding of central section (102) andcreates a taper in section (104) and the taper becomes smaller andsmaller as the axis of the coil proceeds. The coil may have a pitch(105) which is fairly loose, that is to say, that the distance betweenwindings in the secondary shape are at least equal to the diameter ofthe primary coil making up those helical windings. This "looseness"prevents the coil from forming a fixed or pipe-like mass so readilyafter it has been placed within the human body. This looseness alsocreates a secondary shape having a fairly large mass in the vasculaturewhich decreases the length of the coil placed within the catheter so todecrease the amount of friction encountered when deploying the coil. Atightly wound coil producing the same deployed coil volume may not bedeployable because they simply refuse to be pushed through the catheterusing normal pushing techniques. The loose wind discussed here isdesirable but not required.

The angle of the coil (106) may be virtually any value between 10° andapproaching 90°. Indeed in some variations of the invention which may beconsidered to be variations having non-conic ends, the end section needonly be a spirally wound disk.

The material used in constructing a vaso-occlusive member may be any ofa wide variety of materials; preferably, the material chosen is a wireof a radio-opaque material such as a metal or polymer. Suitable metalsand alloys for the wire making up the device (100) include the PlatinumGroup metals, especially platinum, rhodium, palladium, rhenium, andother bio-compatible metals such as tungsten, gold, silver, tantalum,and alloys of these metals. These metals have significant radio-opacityand their alloys may be tailored to accomplish an appropriate blend offlexibility and stiffness. Highly preferred for this service is aplatinum/tungsten alloy.

The wire may also be of any of a wide variety of stainless steels ifsome sacrifice of radio-opacity may be tolerated. Very desirablematerials of construction, from a mechanical point of view, arematerials which maintain their shape despite being subjected to highstress. Certain "super elastic alloys" include nickel/titanium alloys(48-58 atomic % nickel and optionally containing modest amounts ofiron); copper/zinc alloys (38-42% zinc); copper/zinc alloys containing1-10% by weight of beryllium, silicon, tin, aluminum, or gallium; ornickel/aluminum alloys (36-38 atomic % aluminum). Particularly preferredare the alloys described in U.S. Pat. Nos. 3,174,851; 3,351,463; and3,753,700. Especially preferred are the super elastic nickel titaniumalloys, particularly known as "nitinol". These nickel titanium alloysare very sturdy alloys which will tolerate significant flexing withoutplastic deformation even when used as a very small diameter wire.

If a super elastic alloy such as nitinol is used in the device, thediameter of the coil wire may be significantly smaller than that usedwhen the relatively more ductile platinum or platinum/tungsten alloy isused as the material of construction.

The coils may be of radiolucent fibers or polymers (or metallic threadsor wires coated with radiolucent or radio-opaque polymers) such asDacron (polyethylene terephthalate or PET), polyglycolic acid,polylactic acid, fluoropolymers such polytetrafluoroethylene, or Nylon(polyamide), or even silk or cotton. Should a polymer be used as a majorcomponent of the vaso-occlusive member, it is desirably filled with someamount of a known radio-opaque material such as powdered tantalum,powdered tungsten, bismuth oxide, barium sulfate, and the like.

The coil material is first wound into a primary coil form. The primarycoil is typically linear after it has been wound and heat treated.Generally speaking, when the device (100) is formed of a metallic coiland that coil is a platinum alloy or a super elastic alloy such asnitinol, the diameter of the wire used in the production of the coilwill be in the range of 0.0005 and 0.006 inches. The wire of suchdiameter is typically then wound into a primary coil having a primarydiameter of between 0.005 and 0.025 inches. For most neurovascularindications, the preferable diameter is between 0.010 and 0.018 inches.The axial length of the primary coil will usually fall in the range of0.5 to 100 cm, more usually 2.4 to 40 cm. Depending on usage, theprimary coil may well have 10 to 75 turns per centimeter, preferably 10to 40 turns per centimeter. All of the dimensions here are provided onlyas guidelines and are not critical to the invention. However, onlydimensions suitable for use in occluding sites within the human body areincluded in the scope of this invention. The overall diameter of thedevice as deployed is generally between 3 and 25 millimeters with arange between 3 and 12 millimeters much more common. If this device isused within an aneurysm in the cranial vasculature, these shapes may betreated using devices having those diameters. Of course, such diametersare not a critical aspect of the invention.

FIG. 2 shows another variation of the inventive device (200). In thisvariation, the center section (202) is two or more times the length ofthe axial length of the conical end sections (204, 206). The variation(200) also obviously has two opposing ends or sections (204, 206) whichare helically wound and have an overall conical shape which is smallestat the opposing extremities of the device. We have found that in someinstances, it is desirable to provide a short "tail" such as (208) onthe end of the coil which last exits the delivery catheter. This tail(208) prevents the secondary coil turn from hanging in the cathetermouth since the last portion of the device seen by the catheter isstraight. The wire in this instance is continuous throughout each of thesections of the device.

FIG. 3 shows another variation (300) of the inventive device. In thisvariation, the central section (302) is quite short in axial length andhas but little more than one turn of the coil in the secondary shapewithin central section (302). Terminal conical section (304) is,perhaps, three times the axial length of center section (302). Theopposing end section (306) is also quite short in axial length. Theangle of the cone in this variation is found in conical end (306) canapproach 90 degrees.

Also contemplated in this invention is the attachment of various fibrousmaterials to the inventive device for the purpose of addingthrombogenicity to the resulting assembly. A wide variety of fibrousmaterials have been used in adding to the thrombogenicity of such coils.Including in this group are such well known materials as Dacron(polyethylene terephthalate), polyethylene, polypropylene, silk, Nylon,and cotton.

The fibrous materials may be added in a variety of ways, FIG. 4 shows across section of the device shown in FIG. 3 and it shows that thefibrous materials (308) found therein are looped around in such a waythat they are continuous from end to end and generally may be tied tothe end of the coil. Another variation is had by tying the tuft orwrapping the tuft through the turns of the primary coil. Tufts may betied at multiple sites throughout the coil to provide a vast area ofembolus forming sites.

FIG. 5 shows a close up of a primary coil (310) having a number of tufts(312) passing through the primary turns of the coil and merely beingheld in place by turns of the coil itself.

The primary coil may be covered by a fibrous braid such as is shown inU.S. Pat. No. 5,382,259, issued Jan. 17, 1995, to Phelps and Van.

As was noted above, many vaso-occlusive coils are held in place beforedeployment in a variety of different ways so to provide a control on thesite and time of their deployment. Variations of the invention includethe use of electrolytic detachment joints such as is shown in FIG. 6 andmechanical detachment joints such as is shown in FIG. 7.

Specifically, the electrolytic joint shown in FIG. 6 is described insignificant detail in patent such as U.S. Pat. Nos. 5,122,136 and5,354,295, both to Guglielmi discussed above. In these variations, aninsulated pusher (402) is attached to the vaso-occlusive coil (404) viaan electrolytically erodible joint (406). A direct current is applied topusher (402). The current path is, in part, through joint (406) into theionic medium surrounding the coil upon deployment. Such ionic medium is,in the vasculature, blood or saline solution passing through thedeploying catheter. Joint (406) erodes and allows vaso-occlusive device(406) to remain in the body. Vaso-occlusive device (406) may be any ofthe devices described above with respect to this invention.

Similarly, FIG. 7 shows a mechanically detachable assembly (410)partially housed within a deployment catheter (412). The vaso-occlusivedevice itself (414) has an end clasp (416) which engages a similar endclasp (418) forming the end of pusher (420). When pusher (420) isforwarded distally so that both clasp (416) and clasp (418) are exteriorto catheter (412), the vaso-occlusive device (415) with its attachedclasp (416) is free to stay at the chosen site within the human body.Again, vaso-occlusive portion (414) may be any of the devices describedabove in relation to this invention.

In summary, the manner in which this device is employed or deployed maybe found in a variety of other prior publications. In particular, thereader is directed to Ritchart et al., discussed above.

Modification of the above-described variations of carrying out theinvention that would be apparent to those of skill in the fields ofmedical device design generally, and vaso-occlusive devicesspecifically, are tended to be within the scope of the following claims.

We claim as our invention:
 1. A vaso-occlusive device comprising aprimary coil having a plurality of helically wound turns wherein saidprimary coil further comprises a helically wound secondary structurehaving at least one substantially conical portion, each said at leastone substantially conical portion having a small end and a large end,each said large end adjacent a central cylindrical section having adiameter approximating the conical portion large ends.
 2. Thevaso-occlusive device of claim 1 wherein the helically wound secondarystructure comprises two opposing substantially conical portions eachwith a small end and a large end and wherein each such large end isadjacent said central cylindrical section.
 3. The vaso-occlusive deviceof claim 2 where at least a portion of the helically wound secondarystructure has a pitch, the helically wound primary coil has a diameter,and the secondary structure has a pitch which is at least twice theprimary coil diameter.
 4. The vaso-occlusive device of claim 2 furthercomprising a plurality of fibers fixedly attached to said helicallywound primary coil.
 5. The vaso-occlusive device of claim 4 wherein thefibers comprise tufts.
 6. The vaso-occlusive device of claim 6 whereinthe plurality of fibers are looped from turn to turn in said helicallywound primary coil.
 7. The vaso-occlusive device of claim 2 wherein saidhelically wound primary coil has at least one detachable end.
 8. Thevaso-occlusive device of claim 7 wherein the detachable end iselectrolytically erodible.
 9. The vaso-occlusive device of claim 7wherein the detachable end is mechanically detachable.
 10. Thevaso-occlusive device of claim 2 wherein the two opposing substantiallyconical portions adjacent said central cylindrical section are terminalon said device.
 11. The vaso-occlusive device of claim 2 wherein atleast one conical portion further comprises a linear section of primarycoil adjacent the small end of said at least one conical portion. 12.The vaso-occlusive device of claim 1 where at least a portion of thehelically wound secondary structure has a pitch, the helically woundprimary coil has a diameter, and the secondary structure has a pitchwhich is at least twice the primary coil diameter.
 13. Thevaso-occlusive device of claim 1 further comprising a plurality offibers fixedly attached to said helically wound primary coil.
 14. Thevaso-occlusive device of claim 1 wherein said helically wound primarycoil has at least one detachable end.
 15. The vaso-occlusive device ofclaim 1 wherein the at least one conical portion further comprises alinear section of primary coil adjacent the small end of said at leastone conical portion.